It has been shown in a large scale epidemiological study that ureaplasmal infection of the female partner is significantly associated with infertility due to "male factors" as defined by low sperm counts, low viability of spermatozoa, poor sperm motility, poor post-coital tests, or chronic prostatitis. The goal of the present proposal is to intensively characterize this subpopulation of ureaplasmal infected infertile couples in comparison to well-defined control populations in order to determine if the relationship between "male factor" infertility and ureaplasma is causal or coincidental. In both the male and female partners, each serotype of ureaplasma will be quantitated using serotype specific monoclonal antibodies, and the levels of each class of antibody to ureaplasmas and class specific anti-sperm antibody will be determined in serum and local secretions by ELISA. In addition for the male, sperm motility will be quantitated objectively by the recently developed turbidometric assay, sperm morphology and viability will be examined, and localization of mycoplasmas and/or antibody on spermatozoa will be determined. In the female partner, cervical factors will be measured, and the interactions of spermatozoa and cervical factors will be examined in vivo and in vitro. All of these parameters will be correlated so as to allow detection of important differences in test and control populations. Valuable secondary information will be gained in regard to the clinical value of recently developed quantitative techniques and the relationship of antibody levels (specifically anti-sperm antibodies) to infertility.